WASP-12b: Shine on you crazy diamond planet

December 8th, 2010

In this artist's concept of a tar-covered carbon planet, a meteor impact has exposed a diamond layer in the planet's interior. For permission to reproduce this figure, please contact Lynette R. Cook at lynette@spaceart.org. Credit: Lynette Cook (extrasolar.spaceart.org)

“There is no use trying, said Alice; one can’t believe impossible things. I dare say you haven’t had much practice, said the Queen. When I was your age, I always did it for half an hour a day. Why, sometimes I’ve believed as many as six impossible things before breakfast.”

This just in from our Department of Impossible Things: carbon-soaked planets harboring rock formations glittering with diamonds instead of quartz or other silicate minerals common on Earth. Imagine dark gray plains of graphite. Bubbling pools of tar. A smoggy methane atmosphere.

“Astronomers have discovered that a huge, searing-hot planet orbiting another star is loaded with an unusual amount of carbon. The planet, a gas giant named WASP-12b, is the first carbon-rich world ever observed. The discovery was made using NASA’s Spitzer Space Telescope, along with previously published ground-based observations.“

Here at Goddard, exoplanet researcher Marc Kuchner received the news with barely concealed glee. In years past, his work contributed to establishing the hypothetical existence of carbon planets. The WASP-12b observations confirm it.

The implications are exotic. Weird things happen when the ratio of carbon to oxygen in a planetary system crosses the tipping point — that being a ratio greater than 1 to 1.

“When the relative amount of carbon gets that high, it’s as though you flip a switch, and everything changes,” Kuchner explains. “Everything would be different — like imagine, one day you’re a Yankees fan, the next day, Red Sox.”

WASP-12b is a gas giant, so its carbon-rich creations swirl within oceans of dense atmosphere. But what about terrestrial (i.e., rocky) carbon planets? Now it gets mighty interesting.

“If something like this had happened on Earth when it was formed,” Kuchner says, “your expensive engagement ring would be made of glass, which would be rare, because the atmosphere would be made of smog and the mountains would all be made of diamonds.”

Artist’s conception of the dust and gas disk surrounding the star Beta Pictoris. A giant planet may have already formed and terrestrial planets may be forming. The inset panels show two possible outcomes for mature terrestrial planets around Beta Pic. The top one is a water-rich planet similar to the Earth; the bottom one is a carbon-rich planet, with a smoggy, methane-rich atmosphere similar to that of Titan, a moon of Saturn. A team led by Aki Roberge of NASA’s Goddard Space Flight Center first presented the observation in the June 8, 2006, issue of Nature. Credit: NASA/FUSE/Lynette Cook

Kuchner says he thought initially carbon planets would probably be found in exotic stellar environs, like planetary systems whirling around pulsars or white dwarf stars. “But WASP 12 seems to be a pretty normal star, similar to the sun. If it could happen there, it could have happened here. And now that we know WASP-12b is a carbon planet. I bet we’ll start finding others.”

Well, that sounds familiar. In the early days of exoplanet discovery, we found “hot Jupiters,” gas giant planets orbiting shockingly close to their host stars. They seemed exotic until we started finding them all over the place. Now it’s “another day, another hot Jupiter.”

So perhaps carbon-rich planets won’t seem so strange someday, too. Case in point: a star called Beta Pictoris. Kuchner says Beta Pic is “mostly quite similar to the sun, but which has a planetary system and a disk around it that’s carbon rich. Not just a little carbon rich. It has nine times as much carbon as oxygen. That’s even more carbon-rich than WASP-12b.”

We can only imagine what a planet might look like in such a carbon-mad place. We may never know, but it’s fun to wonder. The WASP-12b discovery gives us permission. “People sort of didn’t take the carbon planets idea seriously at first,” Kuchner says, “but this changes things.”

RIGHT: This image of the circumstellar disk around Beta Pictoris shows (in false colors) the light reflected by dust around the young star at infrared wavelengths. The Beta Pic disk is very likely an infant solar system in the process of forming terrestrial planets. Credit: Jean-Luc Beuzit, et al. Grenoble Observatory, European Southern Observatory
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OH AND DID I MENTION?All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.